EMG and Usability Assessment of Adjustable Stiffness Passive Waist-Assist Exoskeletons for Construction Workers

Construction workers experience high rates of low back muscle strain due to frequent lifting of heavy objects. This study examined the effectiveness of an adjustable stiffness passive waist-assist exoskeleton (WIBS) in reducing muscle activity during lifting tasks. Ten male participants performed lifting and lowering tasks both with and without the WIBS. Muscle activity in the thoracic/lumbar erector spinae and multifidus muscles was measured using electromyography. The study also assessed the usability of the exoskeleton. The results revealed that WIBS significantly reduced low back muscle activity by up to 12.5% during lifting and 15.5% during lowering of 10 kg objects, particularly at stiffness levels 2 and 3. Notably, no significant difference was observed at the free and level 1 settings. While increasing stiffness generally decreased muscle activity, there was no significant difference between stiffness levels. The participants positively rated the exoskeleton, with an average satisfaction score of 84.6 across various aspects, including suitability, stability, safety, comfort, and effectiveness. These findings suggest that WIBS could be a valuable tool for reducing muscle strain and the risk of musculoskeletal disorders in construction workers. Longitudinal studies are required to evaluate the long-term use of this technology by construction workers and its effectiveness in a wider range of construction tasks.